Equibiaxial Extension of Two Polymer Melts: Polystyrene and Low Density Polyethylene

Soskey, P. R.; Winter, H. Henning

doi:10.1122/1.549799

Cited by 102 publications

(45 citation statements)

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“…On the remaining three polymers~ linear low density polyethylene (LLDPE), a different polystyrene (PS) and a different low density polyethylene (LDPE) only step shearing and step biaxial extensions were performed. Data for the last two melts were obtained from Soskey and Winter [8,9]. Relevant information on all six melts are presented in table 1.…”

Section: Methodsmentioning

confidence: 99%

“…We have measured stresses following step shear and biaxial strains on each of the three materials for which Laun had previously measured stress growth in steady uniaxial extension [3]. To broaden the data base for comparative analyses, we consider Winter's [8,9] data from step biaxial extension and step shearing of two other melts, as well data we have measured in step biaxial and step shearing on yet another sample. The uniaxial viscosities and the damping functions obtained from the step strain experiments are interpreted with a differential constitutive model developed by Larson [10] that has one adjustable parameter.…”

Section: Introductionmentioning

confidence: 99%

“…In other melts, onset of strain hardening occurs at strains close to one [3]. Papanastasiou et al [7], and more recently Soskey and Winter [8,9] and Winter and Holly [10] have measured stresses in both shear and biaxial extension on the same materials. No data in uniaxial extension, however, were obtained for any of these materials.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the rheology of polymer melts in shear, and biaxial and uniaxial extensions

1987

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Abstract:The experimental properties of different polymer melts, polystyrene, high density polyethylene and low density polyethylene are compared for the first time in three different deformations: step shear, step biaxial extension and steady uniaxial extension. Properties of three other melts are also studied in step biaxial and shear experiments. For our comparative purposes some data of Laun and Winter from the literature are used, as well as new data reported here. In all the step strain experiments, the stresses can be factored into a time dependent relaxation modulus and a strain dependent damping function. The data are interpreted using a differential constitutive equation of Larson which satisfies this time-strain separability and has a single parameter that describes the strain softening character of the material. Results show that differences in the properties of the melts are most pronounced in uniaxial extension and least in biaxial extension. All melts follow the Doi-Edwards prediction relatively closely in biaxial extension. In uniaxial extension, the branched material shows a strong strain hardening effect although its shear and biaxial properties are similar to the other melts. The constitutive model gives a reasonably good fit to the data in all three deformations for unbranched materials for the same value of the adjustable parameter; the model, however, fails for the branched low density polyethylene.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of the rheology of polymer melts in shear, and biaxial and uniaxial extensions

1987

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“…In the solid-like region, the film is characterized by a growing relaxation modulus. Soskey and Winter (1985) reported that the extensional relaxation modulus and the shear modulus have similar time dependence in the linear viscoelastic range. Catstiff et al (1956) reported that the relaxation modulus grows faster and spreads over a narrower range of temperature for polymers with higher crystallinity.…”

Section: Constitutive Equation For the Solid-like Phasementioning

confidence: 99%

Computer simulation of the film blowing process incorporating crystallization and viscoelasticity

Muslet¹,

Kamal²

2004

Journal of Rheology

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“…The damping functions calculated from this potential function are compared to the experimental damping functions in figure 1. The correct amount of strain softening is predicted for all three types of deformation; the Wagner damping function fitted to uniaxial extension predicts too much strain softening in biaxial extension [2]. The Wagner model also predicts a zero second normal-stress difference.…”

mentioning

confidence: 98%

The BKZ as an alternative to the Wagner model for fitting shear and elongational flow data of an LDPE melt

Larson

Monroe²

1987

Rheol Acta

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Rheol. Acta, 23, 10-13 (1984) It was claimed that a separable BKZ model, with a potential function given in Eq. (21), fits the damping function in uniaxial extension and shear for Melt I, as well as the Wagner model fits these damping functions. The plot of the fit for uniaxial extension, figure 2 of Larson and Monroe, however, is in error; the fit is actually poor. A potential function, u, that does yield a good fit, not only to shear and uniaxial extensional data, but to biaxial [1] as well, iswhereandwith Co = 0.20, cl = 0.05, c2 = 0.121, and ~ = 0.1.11 and 12 are the first and second invariants of the Finger strain tensor. The damping functions calculated from this potential function are compared to the experimental damping functions in figure 1. The correct amount of strain softening is predicted for all three types of deformation; the Wagner damping function fitted to uniaxial extension predicts too much strain softening in biaxial extension [2]. The Wagner model also predicts a zero second normal-stress difference. Eqs. (1-3) give a negative second normal-stress difference; the predicted ratio of

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Equibiaxial Extension of Two Polymer Melts: Polystyrene and Low Density Polyethylene

Cited by 102 publications

References 0 publications

Comparison of the rheology of polymer melts in shear, and biaxial and uniaxial extensions

Comparison of the rheology of polymer melts in shear, and biaxial and uniaxial extensions

Computer simulation of the film blowing process incorporating crystallization and viscoelasticity

The BKZ as an alternative to the Wagner model for fitting shear and elongational flow data of an LDPE melt

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